Telephone system



p 7, 1937. H. HOVLAND 2,092,513

} TELEPHONE SYSTEM Filed March 26, 1935 2 Sheets-Sheet l FIG. 1

INI/EN TOR y H. HO l LAND iwzw A T TORNEY H. HOVLAND TELEPHONE SYSTEMSep t. 7, 1937.

Filed March 26, 1955 2 Sheets-Sheet 2 FIG. 2

LF-l INVENTOR H. HOVLAND A TTORNEY Patented Sept. 7, 1937 TELEPHONESYSiTEll/l Henry Hovland, Williston Park, N. Y., assignor to BellTelephone Laboratories, incorporated, New York, N. Y., a corporation ofNew York Application March 26, 1935, Serial No. 13,072

8 Claims.

This invention relates to telephone systems and particularly to thosehaving automatic switches for establishing the connections.

The objects are to improve the release conditions in dial telephonesystems; to distinguish between different classes of called lines, suchas those to subscribers and those to operators positions, and topreparethe release circuits accordingly; and-to effect other improvements insystems of this kind. f

, It has been proposedheretofore to, place'the immediate release or" theentire connection, in cluding the connector switch, under control of thecalling subscriber and at the same time to provide for the release ofthe connector switch at the end of a timed interval after the calledparty disconnects in case the calling party delays in replacinghis-receiver. Systems have also been devised such that, when a call ismade to a line that is disconnected and out of service, the connectorswitch on reaching the line ter minals detects this condition and omitsto out through the talking circuit in the regular way but starts a linefinder instead to find the connector involved for the purpose ofextending the call to an intercept operators position.

According to the present invention certain advantages are attained insystems of this character by an arrangement in which the relay in theconnector that cuts through the connection to a called subscribers linealso prepares a circuit for a time-measure device so that the calledparty may control the release of theconnection independently of thecalling party, and in which said relay by failing to operate when a callis made to' a disconnected line enables the closure of a circuit tostart a finder to search for the connector and to extend the call to anintercept position.

'Another ieature oi the invention is a system of the foregoing characterin which the timing mechanism is rendered ineffective on calls extendedto the intercept operator, and the calling party is given sole controlover the release of the entire connection.

These and other features of the invention will be more fully describedin the following description taken in connection with the accompanyingdrawings and will also be more clearly understood. from the appendedclaims.

In Fig- 1 of the drawings acalling line, a line finder, and twoselectors are shown diagrammatically; and a part of a connectorswitch isshown in detail.

Fig. 2 shows the remainder of the details of off relay 28!.

the connector switch and two subscribers lines appearing in saidconnector, one of which 1s wired for regular service and the other forintercept service. This figure also shows schematically an interceptoperators position together with a finder switch and other circuits forextendingintercepted calls to said position.

Referring particularly to the drawings, the connector switch Cl-C2 isarranged according to this invention to provide the featureshereinbeiore stated. At the left of. Fig. 1 is indicated the telephoneHit of a calling subscriber, with associated. dial We, and lineconductors [35. The line res may be extended to connector Cl- C2 by wayor line finder LF and local selectors Si and S2. The selector S2 is in agroup of selectors having access to connector Cl-CZ by way of multipleterminals Hi6. Terminals lll'l are not accessible to selectors in thegroup in which selector S2 is located, but are accessible to localselectors of another group which are not shown. Similarly toll selectorTS is in a group having access to terminals ill). Terminals iii are notaccessible to selectors in the group in which TS is located, but areaccessible to toll selectors of another group which are not shown. Theconnector circuit Ci-C2 is arranged so that one group of selectors mayconnect through to upper connector bank terminals and the other groupthrough to lower bank terminals as will be hereinafter explained. Thetip, ring and sleeve conductors of (Ii-02, shown in Fig. 2, have accessthrough contacts of brush selecting relay Zfii to upper brushes 263 orlower brushes 202, according to whether the connector was seized bywayof terminals It! or ill) on the one hand or by Way of terminals Hit orill on the other hand. Said lower brushes have access to terminalsconnecting with line conductors 205 and said upper brushes have accessto terminals connesting with line conductors 20 5. Line 205 is that of asubscriber receiving regular service, while line 2% is that of asubscriberwhose service has been discontinued, the discontinuance ofservice being effected by disconnecting the sleeve terminal from thewinding of the associated cut- The finder LF-l routes calls from theconnector to the intercept position when the connector brushes connectto the terminals of lines, such as line 205, which are re- 7 moved fromservice by the aforesaid disconnection of the associated cut-off relays.Line finder LFl extends the call to jack 2%, to which an interceptingoperator has access with the cord circuit 201.

Referring to the timed release feature aforementioned, when relay I [IIreleases due to the disconnection of the called subscriber, while relayl 32 is still operated because the calling subscriber has failed todisconnect, a connection is made to interrupter lead i638. As will behereinafter described, the arrangement shown functions so that, after apredetermined interval following the grounding of lead I88 byinterrupter I58, the connector circuit and all other preceding circuitsof the established connection are caused to release.

Let it be assumed that subscriber E03 desires to call subscriber 222 andhas extended the connection in the usual manner through line finder LFand selectors Si and S2 to selector terminals It?- to which areconnected the conductors of connector CIC2. Relay IE2 now operatesthrough a circuit traceable from battery through the lower winding ofrelay E62, lower inner break contacts of relay IEli, thence over theloop established through the telephone i E13, through the upper innerbreak contacts of relay WI and upper winding of relay I02 to ground.Relay H12 in operating operates relay I I2 through a circuit frombattery through the Winding of relay Il2, contact springs IIS of relayM4, to ground on the front contacts of relay I02. Relay IE2 in operatingconnects a guarding ground to sleeve terminals Hi6 and i8? through itsinner and outer lower make contacts respectively. The ground on sleeveterminal tilt; is extended to sleeve terminal Ill through lower backcontacts of relay I8l, and the ground on sleeve terminal i8? is extendedto sleeve terminal I I t through upper inner back contacts of relay I85.The calling subscriber now actuates the dial IFJ I to dial the tensdigits of the called number. On the first break of the dial contacts,relay H32 releases, but relay H2, which is slow releasing, remainsoperated, connecting a ground pulse from the back contacts of relay 5&2,through upper inner operated make contacts of relay M2 to conductor I69,thence through normally closed contacts of vertical-off-normal springs208, over conductor 2H and through windings of relay H5 and Verticalmagnet MS to battery. Relay H5 operates and vertical magnet Ht causesthe shaft of the connector switch to step upward one step. In order toassist the pulse furnished over relay II5 from the back contacts ofrelay Hi2, a supplementary ground pulse is connected to conductor I69through double dog springs 2G9. Upon a slight upward movement of theswitch shalt, springs 269 are closed, and remain closed until the shafthas taken a complete step, when the double dog drops into the ratchet ofthe shaft and opens springs 289. The aforesaid supplementary groundpulse is connected from ground on the lower outer springs of relay H2,through left-hand break contacts of release magnet 2E0. double dogsprings 269 to conductor H39. This pulse help arrangement is not a partof this invention but is covered in my copending application filed June20, 1934, Serial No. 731,- 432, granted as Patent 2,006,354, July 2,1935. As the shaft takes its first vertical step the VON springs 2&8 areoperated transferring conductor Hi9 from connection with conductor 2 toconductor 2 H2. The pulsing circuit through the vertical magnet may thenbe traced over conductor 2H2, through lower inner front contacts ofrelay H5, upper back contacts of relay 2K5, and windings of relay H5 andvertical magnet IIB to battery. On the next break of the dial, anotherpulse is transmitted to vertical magnet I I 6 which causes the verticalshaft to take another step upward, sustained as before by thesupplementary pulse through the double dog springs 2G9. Slow releaserelay H5 remains operated during the open period between successivepulses. This action continues until the required number of pulses forthe tens digits has been sent, when the connector brushes will havereached the level in which is located the called line.

After the dialing for vertical stepping has been completed, relay I l5releases, and the pulsing circuit is transferred from the verticalmagnet H5 to rotary magnet 2M. This circuit is traceable from pulseconductor led through lower operated front contacts of VON springs 208,over conductor 2 l2, through lower inner back contacts of relay 1! E5,lower break springs of rotary-off-normal combination 2I5 through windingof rotary magnet 2l4 to battery. The pulsing ground that energizesrotary magnet 2M is also effective from junction point ZIS to operaterelay 2I3. This operating circuit is traced from junction 2I6 throughsprings 2H and ZIB of relay 2I9 and winding of relay 2l3 to battery.Relay 2I3 is slow to release and remains operated during the openperiods between pulses. In operating relay 2 I3 closes a circuit foroperating relay H5, which extends from battery through the winding ofvertical magnet I it, winding of relay ll 5, upper operated frontcontacts of relay 2I3 and resistance 229 to ground. Vertical magnet iit, however, does not operate in this circuit. When relay 2I3 operates,the pulsing circuit is completed through another circuit which may betraced from conductor 2I2, lower inner make contacts of relay 2| 3through winding of rotary magnet 2 M to battery. Relay 2I3 is heldoperated during pulsing from junction point 22I over the circuithereinbefore traced, from junction point 2E6. The pulsing circuitthrough the contacts of relay 2I3, replaces the circuit through thelower RON springs 2I5, when these operate after the first rotarymovement of the switch. The ground pulses transmitted over conductor 2l2cause the switch to rotate in the horizontal direction in the usualmanner until the line of the called subscriber 222 is reached.

The reason for extending the pulse circuit of the magnet 2M through thesprings 2I5 for the first pulse and through front contacts of relay M3for all succeeding pulses of the series is to make it impossible to givethe connector brushes an additional step by sending an additionalimpulse following the units series and the release of relay 2E3 andbefore relay 259 has had time to operate and fully open the rotarymagnet circuit. As soon as the rotary pulses cease, relay 2I3 measuresan interval of time for testing the line. I the line is idle, relay 2E9operates, when relay 2I3 releases, and prepares for ringing. Should anextra impulse be received after the test is completed and the line foundidle and relay E E5 has released, the connector would step to the nextline, except for the fact that the circuit for magnet 2% is now open atsprings 2I5. Let it be assumed now that the brushes 202 are resting onterminals connected with the associated line 205. At the time theselector S2 seized the terminals Illfi it applied ground to conductor II l causing the operation of brush selecting relay 2! through a circuittraceable from battery through resistance 223, lower break contacts ofrelay 2J9, lower winding of relay ZEJI, to ground on conductor In. Thisground is applied to 75 conductor II! to operate relay 20! before relayII2 operates and grounds conductor I22, the effect of ground on'thislatter conductor being to shunt the relay 20I as will appear later. Whenrelay I I2 does operate as already described it grounds conductor IIl tosupply the holding condition after the preliminary ground is removed atthe selector S2. Relay 20I now locks over its upper winding to theconductor Ill. Relay 20! in operating transfers the tip and ringconductors and sleeve conductor 224 from their normal connection withupper brushes 203 to lower brushes 202. Assume now that the called line2&5 is busy. Under this condition ground is found on the associatedsleeve terminal and causes the operation of relay 225 through a circuittraced from battery through the lower winding of relay 225, lower breakcontacts of relay IIlI, lower outer operated make contacts of slowrelease relay 2I3, before this relay can release after completion .ofrotary pulsing, lower outer operated front contacts of relay 2lI toground on sleeve terminal of line 205. When relay 2I3 finally releases acircuit is closed for holding relay 225 operated, which is traced fromconductor 228, through lower inner break contacts of relay 2I3, andlower inner operated make contacts of relay 225 to ground on conductorI22. Relay 225 in operating connects. the usualbusy tone to the line ofthe calling subscriber from ground on the secondary winding oftransformer II8 through lower outer back contacts of relay II9, lowerouter make contacts of relay 225, contacts I20 and I2I of relay M9 tothe ring conductor I29 and thence over the line through station I03 toground through the upper winding of relay I02. Calling subscriber I 03hearing the busy signal hangs up his receiver releasing relay I92, whichreleases relay H2. The release of relay II2 removes ground fromconductors ill and I22 which opens the holding circuit through the upperWinding of relay 2!, which releases, and 'also opens the holding circuithereinbefore traced for relay 225, removes ground from the sleeve ofselector S2, thereby causing its release and that of the precedingswitches and also removes the guarding ground from the sleeve terminalsI91, III], and III of the other selectors. When relay H2 is released itcloses a circuit for energizing release magnet 2I9 which is traced frombattery through winding of, magnet 2I0, middle make contacts of VONcombination 208, springs 226 of relay 2I9, and back contacts of relay H2and I22. The energizing of magnet 2I0 causes the release of theconnector switch, including the restoration to normal of VON springs 298and RON springs 2I5. When magnet ZIB is energized it closes a circuitthrough its right-hand contacts to ground thereby assuring that themagnet will be energized until the switch is completely restored, thatis, until VON springs 208 restore to normal and open the circuit of thewinding of magnet 2).

Let it be assumed now that line 205 is idle. Under thiscondition-battery will be connected to the sleeve terminal of line 205through the winding of cut-off relay 221. When relay 2I3 releases afterthe completion of dialing, a circuit is closed for operating, relay 2I9which is traced from battery on sleeve terminal of line 225, throughsleeve brush 292, lower outer operated make contacts of relay 2ilI,lower outer break contacts of relay 2I3, lower winding of relay 2 I9,lower outer operated make contacts of slow releasing relay I I5 before,this relay releases,

upper inner break contacts of relay I8I to ground on conductor I22.Relay 2I9 in operating looks from battery through its upper winding andup per inner contacts, upper inner normally closed contacts of relay225, upper closed contacts of VON springs 208 to ground on conductorIII. Relay 2I9 in operating also closes the tip and ring conductorsthrough to the contacts of relay II4, connects ground through its lowerinner make contact to conductor 224, thereby making line 205 test busyand holding operated cut-off relay 221, disconnects resistance 223 fromthe lower winding of relay I, disconnects contact spring from spring 2I8and connects it to spring 229, disconnects conductor 230 from thecontacts of relay 225 and connects it to contacts I23 of relay H4 andshort circuits contacts II3 of relay II4, thereby maintaining relay II2operated after its original operating path through contacts H3 is brokenby the subsequent operation of relay II4. Relay 2I9 also connects asource of interrupted ringing current 232 by its contacts 233 to thelower winding of relay H4. The ringing source 232 may comprise analternating-current generator connected in series with battery. Ringingcurrent now passes through said lower winding and lower back contacts ofrelay H4 to the ring conductor passing through operated contacts 234 ofrelay 2 I 9 the-nee through lower inner operated front contacts of relay21, ring contacts 202, ring conductor of line 205, through substation222, tip conductor of line 205, tip contacts 202, upper outer operatedmake contacts of relay 20L contacts 235 of relay 2I9, to

ground on the upper outer back contacts of relay IE4. W'hen subscriber222 removes his receiver from the switchhook in response to theactuation of the ringer at his station relay I I4 operates through itslower winding. Relay H4 is adjusted so that its lower back contacts andits upper outer back contact-s do not break until its upper inner makecontacts are closed. Relay I I4 accordingly locks up from batterythrough its 'upper winding and upper inner make contacts,

called subscribers, the tip conductor being closed through its upperouter front contacts and the ring conductor through its lower frontcontacts. Relay IIJI now operates over a circuit traced from batterythrough the upper winding of relay I9I, upper middle break contacts ofrelay II9, upper outer operated make contacts of relay H4, operated makecontacts 235 of relay 2I9, upper outer operated front contacts of relay20I, tip conductor brush 292 and associated terminal, over line 295,ring conductor brush 222 and as sociated terminal, lower outer operatedfront contacts of relay 20I, operated contacts 234 of relay 2I9, loweroperated front contacts of relay H4, springs I20 and I2I of relay H9,and lower winding of relay IOI to ground. Relay IOI in operatingreverses, with its make before break springs, in the usual manner, thedirection of current flow toward the line of the calling subscriber I03,thereby causing the operation of the associated line message register(not shown).

The hereinbefore mentioned feature of the system whereby, if the callingsubscriber I03 delays in hanging up his receiver'after called subscriber222 has hung up, the entire connection is released, will now bedescribed. When the called R1 of the upper inner subscriber hangs up hisreceiver, the circuit traced hereinbefore through the windings of relayliil is opened, and relay IilI releases. The release of relay IOI closesa circuit for operating relay 225 through its upper winding. Thiscircuit may be traced from battery through resistance I 2 upper outeroperated make contacts of relay I I2, upper outer break contacts ofrelay E I5, operated springs 23! and 236 of relay 2 I9, operated springsI23 of relay H4, upper winding of relay 225, upper outer break contactsof relays IElI and HM to interrupter lead I 08. When interrupter I58momentarily grounds lead IP38, relay 22 5 operates and locks up undercontrol of relay Iill through a circuit traced from battery through thelower winding of relay 225, lower outer break contacts of relay IUI,lower inner normally closed contacts of relay 2I3, lower inner makecontacts of relay 225 to ground on lead I22. Relay 225 in operatingtransfers the upper holding winding of relay 2I9 from sleeve ground onlead ill to lead 231, which is connected to ground on the back contactsof relay 238, which is common to a number of connectors. This transferis effected by means make-befo1'ebreak spring combination of relay 225.Relay 238 operates when interrupter 23S grounds its contacts, whichoccurs at a predetermined interval after interrupter I56 grounds lead568. When relay 238 in operating removes ground from lead 21H, relay 2G9releases. The release of relay 2I9 opens through its upper outer makecontacts the oper" ating circuit for relay H2, which releases. Therelease of relay II2 opens the holding circuit for relay 225,hereinbefore traced, which releases and also removes ground from sleeveterminal I56 thereby causing the immediate release of all switchespreceding the connector and consequently the release of relay Iil2. Therelease of relay II2 also releases relay HG by opening its lockingcircuit, which extends from battery through the upper winding and innermake contacts of relay II4, through contact springs I24 and I25 of relayII9, upper inner break contacts of relay I8I to ground on the lowerinner make contacts of relay H2. The release of relays I02, I2 and 2 I9closes a circuit through release magnet 2 Id, thereby efiecting therelease of the con nector switch in the manner hereinbefore described.

The operation of the system will now be described in reference to thefeature whereby, if the called line is disconnected from service, thecalling subscribers line is connected through a line finder to anintercepting operators position. Let it be assumed now that station 2%,which has been disconnected from service, is called. To effect saiddisconnection the out-oh" relay 28I has been disconnected from theassociated sleeve terminal of the line 29 5, which, it will be observed,is connected to the top set of terminals to which brushes 283 haveaccess. To complete a connection to a top set of terminals, brushselecting relay must remain deenergized which is the condition whichobtains when a selector seizes terminals Ill? and grounds sleeve leadE22 which is connected to battery through the lower outer break contactsof relay 258 and resistance 223. Therefore relay 26! now fails tooperate. When relay |I2 operates and applies ground to conductor IIIbecause said relay 2M is shunted by the ground that has already beenapplied to conductor I22 by the selector at terminals it'll. Assume nowthat the number of station 24!! has been dialed, that brushes 203 haveseized the terminals of line 204 and that the connection is ready to becut through in the manner hereinbefore described in establishingconnection to line 2535. Under this condition relay 2H! will not operatebecause there is no battery on the sleeve terminal of line 254. Whenrelay H5 releases due to the release of relay 2I3, a circuit is closedfrom battery through resistance I24, upper outer make contacts of relayH2, upper outer break contacts of relay H5, springs 23I and 24I of relay2I9, upper outer break contacts of relay 22%;, upper operated RONcontacts 2I5, through Winding of relay 242 to the sleeve terminal ofline finder LF-i. From junction point 243 the circuit branches throughthe lower break contacts of relay 242 and the winding of relay 244 toground. Relay 2%, which is a part of line finder LF-I, operates andcauses line finder LFI to hunt for the connector CIC2. When theconnector is found, ground is connected to the sleeve terminal whichoperates relay 242, connecting tip and ring conductors 2&5 and 246 tointercepting trunk circuit 241, which is represented only in abbreviatedform. The operation of relay 262 opens the circuit of relay 244 whichreleases.

The aforesaid intercepting trunk circuit 247 when connected toconductors 2 55 and 246 causes the functioning of a signal associatedwith jack 2%. inserts the answering plug of cord circuit 207 into jack285 and if required can complete a connection to another line byinserting the calling plug of cord circuit 261 into jack 2 58 of thecalled line. If required to give supervision or to operate the usualmessage register associated with the line of the calling subscriber theoperator will connect a bridge across the line to operate reversingrelay It i. When the intercepting operator removes the plug of cordcircuit 26? from jack 2%, after the conversation is completed theconnection is held by the calling subscriber, and the timed releasefeature hereinbefcre described is not now effective since relay 2 I 9 isnot operated and the circuit for operating relay 225 is open at contacts2st and 235 of relay 259. When the calling subscriber disconnects relaysI62, H2 and 2&2 release, all relays now being restored to normal. Therelease of relays $2 and H2 causes the energizing of release magnet 2E0,which releases the connector switch as hereinbefore described.

The operation of the system will now be described when the connectcrCI-C2 is seized by a toll selector.

Assume now that a toll selector not indicated has seized terminals l E.The upper two terminals are connected to tip and ring conductors 33d andrespectively and the lower two terminals to the sleeve and controlconductors, 39 and I341, respectively. The seizure of the tip and ringterminals causes the operation of relays I02 and idl through a circuittraced from battery through the lower windings of relays I82 and i8l,lower inner break contacts of relay H9 over the ring conductor 32 andthrough the loop of the toll selector back over the tip conductor l3l,through the upper inner break contacts of relay H9 and the upper windingof relay N32 to ground. Relay iSi in operating locks to ground on sleeveconductor it?) through its upper and lower front contacts and connectsground on sleeve conductor I33 through its lower operated make contactsand contacts I24 and I of relay II9 to the control lead I34. Ground isalso connected The operator in responding to this signal through thelower operated contacts of relay I8I to sleeve lead I33 thereby guardingterminals III] against seizure by another selector. R'elay I02 inoperating operates relay IE2 from ground on its front contacts throughoperated contacts I58 of. relay iBI in multiple with break contactsconductors to lower brushes 2B2.

.for operating brush selecting relay 29! which is traced from ground onsleeve terminal III, over conductor I30, lower back contactsof relayISI, and thence over conductor H1 and the circuit hereinbefore traced inconnection with a call from selector S2. Relay 2M operates and looks asbefore, connecting the tip, ring and sleeve The pulsing now proceeds asin the case of a local call, ex-

cept that now on the first vertical pulse relay H4 is also operatedthrough a circuit from battery through the upper winding of relay H4,upper outer break contacts of relay H9, upper inner operated makecontacts of relay H5 to- .sleeve ground on the upper front contacts ofrelay ISI. Let it be assumed now that station 222 is being called andthat the associated line 255 is busy, which is indicated by the presenceof ground on its sleeve conductor. Relay 225 now operates and locks inthe manner hereinbefore described for a local call and now causes theoperation of relay II9 through a circuit traceable from battery throughresistance I24, upper .outor operated make contacts of relay H2, upperouter contacts of relay H5 which released on completion of dialing,contacts 23I and 2 of relay 2I8, upper outer operated front contacts ofrelay 225, upper outer operated contacts of relay I8I and winding ofrelay ii?! to ground on the right-hand terminal of the upper winding ofrelay I8I.

control lead I34 causing a connection to be made to the toll operatorscord circuit (not shown) but relay H4 is still held operated by groundfrom the toll selector over control lead 53 i. Re-

lay .I I 9 also removes the winding of busy tone transformer IIB fromits connection with conductor I51 and connects said conductor i5!through resistance I27 to busy flash interrupter I25. Relay Ilaalsotransfers tip and ring conductors I35 and I36 from connection withlocal tip and ring conductors I28 and i29 to connection with toll tipand ring conductors I3I and I32. Relay II 9 also disconnects from thewindings of relays Hi2 .and ISI the operating circuit for these relayshereinbefore traced over the tip .and ring conductors of the tollselector.

The disconnection is made at the upper and lower inner back contacts ofrelay 6 l9. Another operating circuit is established by relay M9 forrelays H32, and NH which maybe traced from battery through'the lowerwindings of relays I02 and IBI, resistance I31, lower operated middlemake contacts of relay Ii 9, and lower make contacts of relay IBI toground on sleeve conductor I30. r

The operation of relay It?! as hereinbeforev describedcauses a flashingof the toll operators Relay H9 in operating removes V with its contactsI'M and I25 sleeve ground from lower inner operated make contacts ofrelay l i9 to ring conductor I32. The toll operator, on observing theflashing lamp releases the connection at the toll switchboard therebycausing ground to be removed from sleeve conductor 53%. This causes therelease of relays I92, H2, i8], H9, 2515, and 225. Ground is alsoremoved from control lead I 34, releasing relay -I Hi. Release magnet isnew energized over the circuit hereinbefore traced in describing thesystem for a local ,call, thereby restoring all apparatus to normal.

The system will now be described for the condition existing when calledstation 222 is idle. Let it be assumed that the terminals of line 205have been seized by the brushes 252 as hereinbefore described. Batterythrough the winding of cut-off relay 22'! is now found on the sleeveterminal of line 205 and it causes the operation of relay 2I9 ashereinbefore traced in connection with a local selector, except that nowthe operating ground is'obtained from sleeve conductor I30 through thelower operated make contacts of relay I8I. Relay 2I9 in operating looksthrough its upper winding and performs the various functions describedbefore and now also operates relay I I9 through a circuit from batterythrough the winding of rotary magnet 2M, contacts 2H and 229 of relay2I9, upper outer make contacts of relay I8I and winding of relay II!) toground on the upper inner operated make contacts of relay I8I. scribedexcepting now the busy flash interrupter 126 is ineffective due to thenon-operation of relay 225, which operated when line 255 was assumed tobe busy. Accordingly, the removal from the control lead I34 of sleeveconductor:

ground by contacts I24 and I25 of relay H9 causes the aforesaid tolloperators lamp to light steadily as an indication that the terminals ofthe called line have been seized and that the called subscribers stationmay now be rung. When the toll operator rings, the holding ground forrelay H4 over control lead I34 is removed and relay II4 releases,thereby establishing the ringing circuit for ringing the station ofsubscriber 222 as hereinbefore described in connecxi tion withthe callfroma local selector. When the called subscriber in answering removeshis receiver from the switchhook relay II l operates as before andcompletes the conversational con- Relay II9 functions asbeforedenection. It will be noted that the timed release .x"

feature, described in connection with a local call is not now effective,as, interrupter lead Hi8 is now disconnected at the upper break contactsof relay IBI. Accordingly, the holding of the connection is under theexclusive control of the calling toll operator. When the toll operatorreleases the toll selector, ground is removed from sleeve conductor I30which deenergizes the upper winding of relay IilI and the circuitthrough the lower windings of relays I02 and I8I is also opened. RelaysI02 and I8I release. The release of relay I92 releases relay H2 and therelease of relay I8I releases relay H9. Relay H4 releases when ground isremoved from control lead I34 and relays 2I9 and 2IJI release when relayE8I releases. The release magnet is energized over the circuithereinbefore described restoring'the connector switch to normal.

The system has been described for a call by a toll selector in a grouphaving access to the connector leads of terminals Hi. It will now bedescribed for a call by a selector in a group having terminals ilil. Inthis case brush selecting relay 20! does not operate, as ground onsleeve conductor E33, which is connected through the upper inner breakcontacts of relay E8! to conductor I22, grounds the battery side of thelower winding of relay 20!. Connection is now established through theback contacts of relay 2M and brushes 2823 with the terminals of line204 in the same manner as described hereinbefore in the establishment ofthe connection with the terminals of line 295. After connection to saidline 204 is made, relay 219, however, does not operate, as there is nowno battery connected to the sleeve terminal of line 20 1. Accordingly,as hereinbefore described there is a circuit closed from battery throughresistance I24 and the contacts of relays H2, H5, 2I9, 225, RON contacts2l5, lower contacts of relay 242 and winding of relay 244 to ground. Abranch circuit from junction point 254 is also closed, for operatingrelay H9 which may be traced through upper outer break contacts ofrelays 225 and 2 l9, upper outer make contacts of relay IBI, through thewinding of relay H9 to ground on the right-hand upper winding terminalof relay l9l. Relay 244 operates to start line finder LF-| andconnection to the intercepting operator is now established in the mannerdescribed for a local call, except that in this case the tip and ringconductors 265 and 245 are transferred by relay H9 from their normalconnection with conductors I28 and I29 to toll conductors I3! and I32.

What is claimed is:

1. In a telephone system, subscribers lines, an automatic switch forextending calls to said lines, a timing mechanism separate from saidswitch for controlling the release thereof, a second automatic switchfor extending calls incoming to said first switch, and means in saidfirst switch effective when a call is extended to one of saidsubscribers lines to render said timing mechanism operative andeffective when a call is extended to another of said lines to start saidsecond switch in operation.

2. In a telephone system, an automatic switch, selective switching meansfor extending connections to said switch, two subscribers linesappearing in terminal sets in said automatic switch, means for operatingsaid automatic switch to seize the terminals of either of said lines, atiming mechanism for controlling the release of said switch, a secondautomatic switch for further extending connections incoming to saidfirst switch, and relay means associated with said first switch whichoperates to render effective said timing mechanism when the switchseizes one of said sets of terminals and which remains inert to causethe starting of said second automatic switch in operation when thefirst-mentioned switch seizes the other set of terminals.

3. In a telephone system, an automatic switch, means for extendingconnections to said switch, two subscribers lines appearing in terminalsof said switch, one of said lines being connected for service and theother being disconnected from service, means for operating said switchto seize the terminals of either of said lines, a timing mechanism forcontrolling the release of said switch, an operators position, a secondautomatic switch for extending to said position connections incoming tosaid first automatic switch, and relay means which energizes to rendereffective said timing mechanism when the firstmentioned switch seizesone of said lines and which remains deenergized to cause the starting ofsaid second automatic switch in operation when the first-mentionedswitch seizes the other of said lines.

4. In a telephone system, a connector switch, means for extending callsto said switch, two subscribers lines appearing in said switch, one ofsaid lines being connected for service and the other line beingdisconnected from service, means for operating the switch to seizeeither of said lines, mechanism for controlling the release of saidswitch, an operators position, a finder switch for extending to saidposition calls incoming to said connector switch, and means associatedwith said connector switch, the operation of which varies according towhether the switch seizes one or the other of said lines, and meanscontrolled by said last mentioned means either for rendering effectivesaid release controlling mechanism or for starting in operation saidfinder switch.

5. In a telephone system, a connector switch, means for extending callsto said switch, two lines, one of which is and the other of which is notin a condition for receiving calls, means for operating said connectorswitch to seize either of said lines, release mechanism for controllingthe release of said switch, an operators position, a finder switch forextending to said position calls incoming to said connector, a relay insaid connector switch which operates or remains inoperative according towhether the connector seizes one or the other of said lines, a circuitclosed by said relay when operated for rendering effective said releasemechanism, and a circuit closed by said relay when deenergized forstarting said finder switch in operation.

6. In a telephone system, a connector switch, a subscribers lineconnected to a set of terminals of said switch for service, a secondline appearing in a set of terminals in said connector but disconnectedfrom service, means for extending a connection to said connector from acalling party, release means for said connector, a relay in saidconnector operable when the connector seizes the terminals of the linein service, a circuit closed through front contacts of said relay forplacing the release means of said switch under control of the calledline, said relay remaining deenergized when the connector seizes theterminals of the disconnected line, an operators position, a finderswitch for seizing the connection extended to said connector andextending it to said position, a circuit closed through back contacts ofsaid relay for starting said finder in operation, and means forplacingthe operation of said release means under the sole control of thecalling party when said relay is deenergized.

7. In a telephone system, an automatic switch, means for extendingconnections to said switch, two subscribers lines appearing in terminalsets in said switch, means for operating said automatic switch to seizethe terminals of either of said lines, a timing mechanism, a secondautomatic switch for further extending connections incoming to saidfirst switch, a relay in said first switch which operates or remainsinoperative according to whether said first switch seizes one or theother of said lines, a circuit closed by said relay when operated forrendering efiective said timing mechanism, a circuit closed by saidrelay when deenergized for starting said second automatic switch inoperation, means for placing the ceive service and the test circuit ofthe other line being opened to deny service to said line, means foroperating the switch to seize either one of said lines, timingmechanism, an automatic switch for further extending calls incoming tosaid connector switch, a relay for the connector switch which operatesor remains inoperative according to whether the test circuit of thesubscribers line seized is closed or open, a circuit closed by saidrelay when operated for rendering effective said timing mechanism, meanscontrolled by said timing mechanism for causing the release of saidconnector switch, and

a circuit closed by said relay when deenergized 10 for starting saidautomatic switch in operation.

HENRY HOVLAND.

